Low voltage lighting systems are well known. Such systems include a power supply which provides a voltage substantially lower than 110 volts AC, e.g., 12 volts AC. Not only are such low voltage systems safer, they can also be installed by the average homeowner.
Low voltage lighting systems generally include four basic components, as follows: (i) a transformer or power pack for converting 110 volts AC to 12 volts AC (for example); (ii) a control system consisting of a timer and/or photoelectric cell, and optionally a manual on/off switch; (iii) a plurality of light fixtures suitable for mechanical connection to a "ground surface" through the use of a stake or mounting plate, for example; and (iv) a cable for electrically interconnecting the components described above. The present invention is particularly directed toward a low voltage light fixture suitable for use in such low voltage lighting systems.
Low voltage light fixtures preferably include several features. For one thing, even though they are operated at a comparatively low voltage, they should provide adequate light for their intended purpose. The light should be well diffused by a lens or baffle so that "hot spots" are avoided. Hot spots, as that term is used herein, are bright concentrations of light which occur when the fixture's lens or light baffle does not provide a well diffused light but instead provides a light which is much more concentrated in the immediate vicinity of the bulb or tube.
Another desirable feature of low voltage lighting fixtures is that they provide light at the proper height so that landscaping or architectural details can best be illuminated. There are two particularly popular types of low voltage light fixtures, i.e. floodlights and temple lights. Floodlights, or spotlights, provide a fairly narrow, concentrated beam, whereas temple fixtures emanate light outward and downward through the use of louvres. This results in a cone of light having an apex at the top of the fixture and a base on the ground surface. Temple light fixtures must therefore be positioned adjacent to or above the subjects to be illuminated. Thus, for example, it may be desirable to have the temple light immediately above the ground surface to delimit and illuminate a walkway. It may also be desirable to have the temple light located at some preselected distance above the ground plane so that plants and various architectural features can be highlighted.
Of course, in addition to providing the maximum light output available (without hot spots) and being positionable at various heights, low voltage lighting fixtures must also be safe and reliable. Thus, the cable which connects the light fixtures to the transformer should preferably be buried or otherwise encased or enclosed so as to minimize the risk of damaging the cable during lawn mowing or trimming operations, for example.
Low voltage light fixtures must be attractive as well. One of their primary functions is to enhance the attractiveness of homes and businesses; if the lights themselves are unattractive or aesthetically incompatible with the grounds or architecture, the lights will be unacceptable to purchasers and will not fulfill their intended function. In view of the wide variety of tastes and styles, the Applicants believe that low voltage light fixtures should preferably be modular or convertible so that they can be modified to suit the purpose at hand.
Low voltage light fixtures should also be relatively inexpensive; have relatively few parts; and be simple to assemble.
Unfortunately, prior art low voltage lighting fixtures do not possess all of the desirable features discussed above. One type of low voltage lighting fixture, shown in FIG. 1, includes a simple ground stake and a bulb/lens assembly including a translucent lens surrounding an incandescent bulb. The ground stake is typically approximately seven to eight inches long. It tapers to a sharp point and has a "+" or X-shaped cross section. The upper end of the ground stake forms a forked female adapter suitable for slideably receiving a male adapter located at the bottom of the bulb/lens assembly. The cable simply loops over the top of the ground stake, between the upwardly extending tines of the female adapter and beneath the male adapter of the bulb/lens assembly, and small metal prongs (see FIG. 2) depending from the bulb/lens assembly penetrate the cable insulation so as to place the light source (e.g., incandescent bulb) in electrical contact with the conductor. Still referring to the prior art design of FIG. 1, the bulb/lens assembly basically includes a lens surrounding an incandescent bulb, and a plurality of vertically spaced louvres or baffles for directing the light downward. The lens is made of plastic having uniform thickness and translucence over the entire surface thereof. The louvres are fixed and separated by three spanners spaced at 120.degree. intervals around the outer periphery of the lens.
While the light fixture shown in FIG. 1 has proven to be an excellent design, both from aesthetic and safety standpoints, it is perceived that the design can be improved. For example, even though the cable is only exposed for a very short distance, the cable is still not totally enclosed or encased. It is thus partially exposed to the elements and to mowers, weed trimmers and the like. This problem is particularly troublesome when the ground stake is only partially inserted into the ground in an attempt to elevate the light source to a preferred height above the ground.
The type of light fixture shown in FIG. 1 is also disadvantageous because it includes a simple translucent lens of the type which either provides insufficient light output because it is excessively opaque in order to fully diffuse the light, or has "hot spots" because the lens is quite transparent in an attempt to provide the maximum amount of light power. Also, the louvre spanners diminish the net light power provided by the fixture. Finally, the temple light fixture is not modular or convertible in the sense that the louvres can be removed or adjusted to variably provide a "look" consistent with the surrounding architecture of landscape.
In an attempt to solve the exposed cable problem, and to allow the user to position the light source at a preferred height above the ground surface, a "post" was added to the basic ground stake design shown in FIG. 1. FIG. 2 illustrates this improved prior art light fixture. It includes a ground stake suitable for insertion in the ground and an upper male end suitable for insertion into the lower end of a hollow post. A female adapter (functionally analogous to the upper end of the traditional stake shown in FIG. 1) inserts into the top end of the post and a bulb/lens assembly identical to that shown in FIG. 1 slideably connects with the forked female adapter. The cable is therefore substantially encased or enclosed and is insulated from the elements and less likely to be inadvertently damaged. It should be noted that the lower end of the bulb/lens assembly is broken away in FIG. 2 to show one of the small metal cable-puncturing prongs.
While the fixture of FIG. 2 is an improvement over that of FIG. 1 in that the cable is better protected and the light source can be raised to about 18 inches off the ground, the FIG. 2 design still suffers from some disadvantages. One problem is that the light fixture shown in FIG. 2 includes four basic components, the light source or lens/bulb assembly; female adapter; post; and stake. Given the fact that the light source itself includes a plurality of louvres, a lens, and various other components, the design shown in FIG. 2 is relatively costly, primarily due to the number of parts which must be manufactured and stocked. Also, each light fixture requires significant assembly due to the number of parts. To assemble the fixture shown in FIG. 2, there must first be sufficient slack in the cable to insert it through the hollow post and up and over the female adapter. The female adapter is then inserted into the top of the post and the excess cable pulled down through the post. Then, the stake can be inserted into the lower end of the post and the male adapter of the bulb/lens assembly slid into operative contact with the female adapter. Thus, there are several parts to assemble, and considerable extra cable must be available to interconnect an entire string of fixtures.
Another problem with the fixture shown in FIG. 2, and other prior art fixtures, is that the cable-piercing prongs are separate from the bulb socket assembly, with wires running therebetween. In such prior art fixtures, the bulb socket is mechanically connected to the lower louvre assembly. Two wires extend downward from the bulb socket and terminate in wire lugs, which in turn removably attach to the cable prongs. A sectional view of this somewhat cumbersome design is shown in FIG. 10.
Finally, the light fixture shown in FIG. 2 still has efficiency and hot spot problems attributable to the lens and louvre spanner designs and is incapable of being modified or converted to fit various architectural styles.
The present invention addresses the problems associated with prior art low voltage lighting fixtures. In particular, in preferred embodiments the light fixture of the present invention provides a significant amount of light without the nuisance of hot spots. Also, preferred embodiments include an integral stake/post adapter component which is manufactured in a "living hinge" configuration. This results in an inexpensive light fixture which is easy to assemble. Preferred light fixtures according to the invention are also flexible in terms of their aesthetics: one of the louvres can be removed to significantly change the aesthetic impact of the fixture, and to change the net amount of light provided by the light source. Finally, preferred embodiments include integral bulb contact/cable prongs which are inexpensive and reliable.